vio: make remove callback return void

The driver core ignores the return value of struct bus_type::remove()
because there is only little that can be done. To simplify the quest to
make this function return void, let struct vio_driver::remove() return
void, too. All users already unconditionally return 0, this commit makes
it obvious that returning an error code is a bad idea and makes it
obvious for future driver authors that returning an error code isn't
intended.

Note there are two nominally different implementations for a vio bus:
one in arch/sparc/kernel/vio.c and the other in
arch/powerpc/platforms/pseries/vio.c. I didn't care to check which
driver is using which of these busses (or if even some of them can be
used with both) and simply adapt all drivers and the two bus codes in
one go.

Note that for the powerpc implementation there is a semantical change:
Before this patch for a device that was bound to a driver without a
remove callback vio_cmo_bus_remove(viodev) wasn't called. As the device
core still considers the device unbound after vio_bus_remove() returns
calling this unconditionally is the consistent behaviour which is
implemented here.

Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
---
Hello,

note that this change depends on
https://lore.kernel.org/r/20210121062005.53271-1-ljp@linux.ibm.com which removes
an (ignored) return -EBUSY in drivers/net/ethernet/ibm/ibmvnic.c.
I don't know when/if this latter patch will be applied, so it might take
some time until my patch can go in.

Best regards
Uwe

 arch/powerpc/include/asm/vio.h           | 2 +-
 arch/powerpc/platforms/pseries/vio.c     | 7 +++----
 arch/sparc/include/asm/vio.h             | 2 +-
 arch/sparc/kernel/ds.c                   | 6 ------
 arch/sparc/kernel/vio.c                  | 4 ++--
 drivers/block/sunvdc.c                   | 3 +--
 drivers/char/hw_random/pseries-rng.c     | 3 +--
 drivers/char/tpm/tpm_ibmvtpm.c           | 4 +---
 drivers/crypto/nx/nx-842-pseries.c       | 4 +---
 drivers/crypto/nx/nx.c                   | 4 +---
 drivers/misc/ibmvmc.c                    | 4 +---
 drivers/net/ethernet/ibm/ibmveth.c       | 4 +---
 drivers/net/ethernet/ibm/ibmvnic.c       | 4 +---
 drivers/net/ethernet/sun/ldmvsw.c        | 4 +---
 drivers/net/ethernet/sun/sunvnet.c       | 3 +--
 drivers/scsi/ibmvscsi/ibmvfc.c           | 3 +--
 drivers/scsi/ibmvscsi/ibmvscsi.c         | 4 +---
 drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c | 4 +---
 drivers/tty/hvc/hvcs.c                   | 3 +--
 drivers/tty/vcc.c                        | 4 +---
 20 files changed, 22 insertions(+), 54 deletions(-)

Hello Sukadev,

On 1/28/21 8:07 PM, Sukadev Bhattiprolu wrote:
> Slightly off-topic, should ndo_stop() also return a void? Its return value

> seems to be mostly ignored and [...]


I don't know enough about the network stack to tell. Probably it's a 
good idea to start a separate thread for this and address this to the 
netdev list only.

Best regards
Uwe

On 1/27/21 1:50 PM, Uwe Kleine-König wrote:
> The driver core ignores the return value of struct bus_type::remove()
> because there is only little that can be done. To simplify the quest to
> make this function return void, let struct vio_driver::remove() return
> void, too. All users already unconditionally return 0, this commit makes
> it obvious that returning an error code is a bad idea and makes it
> obvious for future driver authors that returning an error code isn't
> intended.
> 
> Note there are two nominally different implementations for a vio bus:
> one in arch/sparc/kernel/vio.c and the other in
> arch/powerpc/platforms/pseries/vio.c. I didn't care to check which
> driver is using which of these busses (or if even some of them can be
> used with both) and simply adapt all drivers and the two bus codes in
> one go.
> 
> Note that for the powerpc implementation there is a semantical change:
> Before this patch for a device that was bound to a driver without a
> remove callback vio_cmo_bus_remove(viodev) wasn't called. As the device
> core still considers the device unbound after vio_bus_remove() returns
> calling this unconditionally is the consistent behaviour which is
> implemented here.
> 
> Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>

Reviewed-by: Tyrel Datwyler <tyreld@linux.ibm.com>

> ---
> Hello,
> 
> note that this change depends on
> https://lore.kernel.org/r/20210121062005.53271-1-ljp@linux.ibm.com which removes
> an (ignored) return -EBUSY in drivers/net/ethernet/ibm/ibmvnic.c.
> I don't know when/if this latter patch will be applied, so it might take
> some time until my patch can go in.
> 
> Best regards
> Uwe
> 
>  arch/powerpc/include/asm/vio.h           | 2 +-
>  arch/powerpc/platforms/pseries/vio.c     | 7 +++----
>  arch/sparc/include/asm/vio.h             | 2 +-
>  arch/sparc/kernel/ds.c                   | 6 ------
>  arch/sparc/kernel/vio.c                  | 4 ++--
>  drivers/block/sunvdc.c                   | 3 +--
>  drivers/char/hw_random/pseries-rng.c     | 3 +--
>  drivers/char/tpm/tpm_ibmvtpm.c           | 4 +---
>  drivers/crypto/nx/nx-842-pseries.c       | 4 +---
>  drivers/crypto/nx/nx.c                   | 4 +---
>  drivers/misc/ibmvmc.c                    | 4 +---
>  drivers/net/ethernet/ibm/ibmveth.c       | 4 +---
>  drivers/net/ethernet/ibm/ibmvnic.c       | 4 +---
>  drivers/net/ethernet/sun/ldmvsw.c        | 4 +---
>  drivers/net/ethernet/sun/sunvnet.c       | 3 +--
>  drivers/scsi/ibmvscsi/ibmvfc.c           | 3 +--
>  drivers/scsi/ibmvscsi/ibmvscsi.c         | 4 +---
>  drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c | 4 +---
>  drivers/tty/hvc/hvcs.c                   | 3 +--
>  drivers/tty/vcc.c                        | 4 +---
>  20 files changed, 22 insertions(+), 54 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/vio.h b/arch/powerpc/include/asm/vio.h
> index 0cf52746531b..721c0d6715ac 100644
> --- a/arch/powerpc/include/asm/vio.h
> +++ b/arch/powerpc/include/asm/vio.h
> @@ -113,7 +113,7 @@ struct vio_driver {
>  	const char *name;
>  	const struct vio_device_id *id_table;
>  	int (*probe)(struct vio_dev *dev, const struct vio_device_id *id);
> -	int (*remove)(struct vio_dev *dev);
> +	void (*remove)(struct vio_dev *dev);
>  	/* A driver must have a get_desired_dma() function to
>  	 * be loaded in a CMO environment if it uses DMA.
>  	 */
> diff --git a/arch/powerpc/platforms/pseries/vio.c b/arch/powerpc/platforms/pseries/vio.c
> index b2797cfe4e2b..9cb4fc839fd5 100644
> --- a/arch/powerpc/platforms/pseries/vio.c
> +++ b/arch/powerpc/platforms/pseries/vio.c
> @@ -1261,7 +1261,6 @@ static int vio_bus_remove(struct device *dev)
>  	struct vio_dev *viodev = to_vio_dev(dev);
>  	struct vio_driver *viodrv = to_vio_driver(dev->driver);
>  	struct device *devptr;
> -	int ret = 1;
>  
>  	/*
>  	 * Hold a reference to the device after the remove function is called
> @@ -1270,13 +1269,13 @@ static int vio_bus_remove(struct device *dev)
>  	devptr = get_device(dev);
>  
>  	if (viodrv->remove)
> -		ret = viodrv->remove(viodev);
> +		viodrv->remove(viodev);
>  
> -	if (!ret && firmware_has_feature(FW_FEATURE_CMO))
> +	if (firmware_has_feature(FW_FEATURE_CMO))
>  		vio_cmo_bus_remove(viodev);
>  
>  	put_device(devptr);
> -	return ret;
> +	return 0;
>  }
>  
>  /**
> diff --git a/arch/sparc/include/asm/vio.h b/arch/sparc/include/asm/vio.h
> index 059f0eb678e0..8a1a83bbb6d5 100644
> --- a/arch/sparc/include/asm/vio.h
> +++ b/arch/sparc/include/asm/vio.h
> @@ -362,7 +362,7 @@ struct vio_driver {
>  	struct list_head		node;
>  	const struct vio_device_id	*id_table;
>  	int (*probe)(struct vio_dev *dev, const struct vio_device_id *id);
> -	int (*remove)(struct vio_dev *dev);
> +	void (*remove)(struct vio_dev *dev);
>  	void (*shutdown)(struct vio_dev *dev);
>  	unsigned long			driver_data;
>  	struct device_driver		driver;
> diff --git a/arch/sparc/kernel/ds.c b/arch/sparc/kernel/ds.c
> index 522e5b51050c..4a5bdb0df779 100644
> --- a/arch/sparc/kernel/ds.c
> +++ b/arch/sparc/kernel/ds.c
> @@ -1236,11 +1236,6 @@ static int ds_probe(struct vio_dev *vdev, const struct vio_device_id *id)
>  	return err;
>  }
>  
> -static int ds_remove(struct vio_dev *vdev)
> -{
> -	return 0;
> -}
> -
>  static const struct vio_device_id ds_match[] = {
>  	{
>  		.type = "domain-services-port",
> @@ -1251,7 +1246,6 @@ static const struct vio_device_id ds_match[] = {
>  static struct vio_driver ds_driver = {
>  	.id_table	= ds_match,
>  	.probe		= ds_probe,
> -	.remove		= ds_remove,
>  	.name		= "ds",
>  };
>  
> diff --git a/arch/sparc/kernel/vio.c b/arch/sparc/kernel/vio.c
> index 4f57056ed463..348a88691219 100644
> --- a/arch/sparc/kernel/vio.c
> +++ b/arch/sparc/kernel/vio.c
> @@ -105,10 +105,10 @@ static int vio_device_remove(struct device *dev)
>  		 * routines to do so at the moment. TBD
>  		 */
>  
> -		return drv->remove(vdev);
> +		drv->remove(vdev);
>  	}
>  
> -	return 1;
> +	return 0;
>  }
>  
>  static ssize_t devspec_show(struct device *dev,
> diff --git a/drivers/block/sunvdc.c b/drivers/block/sunvdc.c
> index 39aeebc6837d..1547d4345ad8 100644
> --- a/drivers/block/sunvdc.c
> +++ b/drivers/block/sunvdc.c
> @@ -1071,7 +1071,7 @@ static int vdc_port_probe(struct vio_dev *vdev, const struct vio_device_id *id)
>  	return err;
>  }
>  
> -static int vdc_port_remove(struct vio_dev *vdev)
> +static void vdc_port_remove(struct vio_dev *vdev)
>  {
>  	struct vdc_port *port = dev_get_drvdata(&vdev->dev);
>  
> @@ -1094,7 +1094,6 @@ static int vdc_port_remove(struct vio_dev *vdev)
>  
>  		kfree(port);
>  	}
> -	return 0;
>  }
>  
>  static void vdc_requeue_inflight(struct vdc_port *port)
> diff --git a/drivers/char/hw_random/pseries-rng.c b/drivers/char/hw_random/pseries-rng.c
> index 8038a8a9fb58..f4949b689bd5 100644
> --- a/drivers/char/hw_random/pseries-rng.c
> +++ b/drivers/char/hw_random/pseries-rng.c
> @@ -54,10 +54,9 @@ static int pseries_rng_probe(struct vio_dev *dev,
>  	return hwrng_register(&pseries_rng);
>  }
>  
> -static int pseries_rng_remove(struct vio_dev *dev)
> +static void pseries_rng_remove(struct vio_dev *dev)
>  {
>  	hwrng_unregister(&pseries_rng);
> -	return 0;
>  }
>  
>  static const struct vio_device_id pseries_rng_driver_ids[] = {
> diff --git a/drivers/char/tpm/tpm_ibmvtpm.c b/drivers/char/tpm/tpm_ibmvtpm.c
> index 994385bf37c0..903604769de9 100644
> --- a/drivers/char/tpm/tpm_ibmvtpm.c
> +++ b/drivers/char/tpm/tpm_ibmvtpm.c
> @@ -343,7 +343,7 @@ static int ibmvtpm_crq_send_init_complete(struct ibmvtpm_dev *ibmvtpm)
>   *
>   * Return: Always 0.
>   */
> -static int tpm_ibmvtpm_remove(struct vio_dev *vdev)
> +static void tpm_ibmvtpm_remove(struct vio_dev *vdev)
>  {
>  	struct tpm_chip *chip = dev_get_drvdata(&vdev->dev);
>  	struct ibmvtpm_dev *ibmvtpm = dev_get_drvdata(&chip->dev);
> @@ -372,8 +372,6 @@ static int tpm_ibmvtpm_remove(struct vio_dev *vdev)
>  	kfree(ibmvtpm);
>  	/* For tpm_ibmvtpm_get_desired_dma */
>  	dev_set_drvdata(&vdev->dev, NULL);
> -
> -	return 0;
>  }
>  
>  /**
> diff --git a/drivers/crypto/nx/nx-842-pseries.c b/drivers/crypto/nx/nx-842-pseries.c
> index 2de5e3672e42..cc8dd3072b8b 100644
> --- a/drivers/crypto/nx/nx-842-pseries.c
> +++ b/drivers/crypto/nx/nx-842-pseries.c
> @@ -1042,7 +1042,7 @@ static int nx842_probe(struct vio_dev *viodev,
>  	return ret;
>  }
>  
> -static int nx842_remove(struct vio_dev *viodev)
> +static void nx842_remove(struct vio_dev *viodev)
>  {
>  	struct nx842_devdata *old_devdata;
>  	unsigned long flags;
> @@ -1063,8 +1063,6 @@ static int nx842_remove(struct vio_dev *viodev)
>  	if (old_devdata)
>  		kfree(old_devdata->counters);
>  	kfree(old_devdata);
> -
> -	return 0;
>  }
>  
>  static const struct vio_device_id nx842_vio_driver_ids[] = {
> diff --git a/drivers/crypto/nx/nx.c b/drivers/crypto/nx/nx.c
> index 0d2dc5be7f19..1d0e8a1ba160 100644
> --- a/drivers/crypto/nx/nx.c
> +++ b/drivers/crypto/nx/nx.c
> @@ -783,7 +783,7 @@ static int nx_probe(struct vio_dev *viodev, const struct vio_device_id *id)
>  	return nx_register_algs();
>  }
>  
> -static int nx_remove(struct vio_dev *viodev)
> +static void nx_remove(struct vio_dev *viodev)
>  {
>  	dev_dbg(&viodev->dev, "entering nx_remove for UA 0x%x\n",
>  		viodev->unit_address);
> @@ -811,8 +811,6 @@ static int nx_remove(struct vio_dev *viodev)
>  		nx_unregister_skcipher(&nx_ecb_aes_alg, NX_FC_AES,
>  				       NX_MODE_AES_ECB);
>  	}
> -
> -	return 0;
>  }
>  
>  
> diff --git a/drivers/misc/ibmvmc.c b/drivers/misc/ibmvmc.c
> index 2d778d0f011e..c0fe3295c330 100644
> --- a/drivers/misc/ibmvmc.c
> +++ b/drivers/misc/ibmvmc.c
> @@ -2288,15 +2288,13 @@ static int ibmvmc_probe(struct vio_dev *vdev, const struct vio_device_id *id)
>  	return -EPERM;
>  }
>  
> -static int ibmvmc_remove(struct vio_dev *vdev)
> +static void ibmvmc_remove(struct vio_dev *vdev)
>  {
>  	struct crq_server_adapter *adapter = dev_get_drvdata(&vdev->dev);
>  
>  	dev_info(adapter->dev, "Entering remove for UA 0x%x\n",
>  		 vdev->unit_address);
>  	ibmvmc_release_crq_queue(adapter);
> -
> -	return 0;
>  }
>  
>  static struct vio_device_id ibmvmc_device_table[] = {
> diff --git a/drivers/net/ethernet/ibm/ibmveth.c b/drivers/net/ethernet/ibm/ibmveth.c
> index c3ec9ceed833..7fea9ae60f13 100644
> --- a/drivers/net/ethernet/ibm/ibmveth.c
> +++ b/drivers/net/ethernet/ibm/ibmveth.c
> @@ -1758,7 +1758,7 @@ static int ibmveth_probe(struct vio_dev *dev, const struct vio_device_id *id)
>  	return 0;
>  }
>  
> -static int ibmveth_remove(struct vio_dev *dev)
> +static void ibmveth_remove(struct vio_dev *dev)
>  {
>  	struct net_device *netdev = dev_get_drvdata(&dev->dev);
>  	struct ibmveth_adapter *adapter = netdev_priv(netdev);
> @@ -1771,8 +1771,6 @@ static int ibmveth_remove(struct vio_dev *dev)
>  
>  	free_netdev(netdev);
>  	dev_set_drvdata(&dev->dev, NULL);
> -
> -	return 0;
>  }
>  
>  static struct attribute veth_active_attr;
> diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
> index a187d51bcf92..2eec0652760c 100644
> --- a/drivers/net/ethernet/ibm/ibmvnic.c
> +++ b/drivers/net/ethernet/ibm/ibmvnic.c
> @@ -5430,7 +5430,7 @@ static int ibmvnic_probe(struct vio_dev *dev, const struct vio_device_id *id)
>  	return rc;
>  }
>  
> -static int ibmvnic_remove(struct vio_dev *dev)
> +static void ibmvnic_remove(struct vio_dev *dev)
>  {
>  	struct net_device *netdev = dev_get_drvdata(&dev->dev);
>  	struct ibmvnic_adapter *adapter = netdev_priv(netdev);
> @@ -5460,8 +5460,6 @@ static int ibmvnic_remove(struct vio_dev *dev)
>  	device_remove_file(&dev->dev, &dev_attr_failover);
>  	free_netdev(netdev);
>  	dev_set_drvdata(&dev->dev, NULL);
> -
> -	return 0;
>  }
>  
>  static ssize_t failover_store(struct device *dev, struct device_attribute *attr,
> diff --git a/drivers/net/ethernet/sun/ldmvsw.c b/drivers/net/ethernet/sun/ldmvsw.c
> index 01ea0d6f8819..50bd4e3b0af9 100644
> --- a/drivers/net/ethernet/sun/ldmvsw.c
> +++ b/drivers/net/ethernet/sun/ldmvsw.c
> @@ -404,7 +404,7 @@ static int vsw_port_probe(struct vio_dev *vdev, const struct vio_device_id *id)
>  	return err;
>  }
>  
> -static int vsw_port_remove(struct vio_dev *vdev)
> +static void vsw_port_remove(struct vio_dev *vdev)
>  {
>  	struct vnet_port *port = dev_get_drvdata(&vdev->dev);
>  	unsigned long flags;
> @@ -430,8 +430,6 @@ static int vsw_port_remove(struct vio_dev *vdev)
>  
>  		free_netdev(port->dev);
>  	}
> -
> -	return 0;
>  }
>  
>  static void vsw_cleanup(void)
> diff --git a/drivers/net/ethernet/sun/sunvnet.c b/drivers/net/ethernet/sun/sunvnet.c
> index 96b883f965f6..58ee89223951 100644
> --- a/drivers/net/ethernet/sun/sunvnet.c
> +++ b/drivers/net/ethernet/sun/sunvnet.c
> @@ -510,7 +510,7 @@ static int vnet_port_probe(struct vio_dev *vdev, const struct vio_device_id *id)
>  	return err;
>  }
>  
> -static int vnet_port_remove(struct vio_dev *vdev)
> +static void vnet_port_remove(struct vio_dev *vdev)
>  {
>  	struct vnet_port *port = dev_get_drvdata(&vdev->dev);
>  
> @@ -533,7 +533,6 @@ static int vnet_port_remove(struct vio_dev *vdev)
>  
>  		kfree(port);
>  	}
> -	return 0;
>  }
>  
>  static const struct vio_device_id vnet_port_match[] = {
> diff --git a/drivers/scsi/ibmvscsi/ibmvfc.c b/drivers/scsi/ibmvscsi/ibmvfc.c
> index 42e4d35e0d35..0a472acaca5d 100644
> --- a/drivers/scsi/ibmvscsi/ibmvfc.c
> +++ b/drivers/scsi/ibmvscsi/ibmvfc.c
> @@ -5253,7 +5253,7 @@ static int ibmvfc_probe(struct vio_dev *vdev, const struct vio_device_id *id)
>   * Return value:
>   * 	0
>   **/
> -static int ibmvfc_remove(struct vio_dev *vdev)
> +static void ibmvfc_remove(struct vio_dev *vdev)
>  {
>  	struct ibmvfc_host *vhost = dev_get_drvdata(&vdev->dev);
>  	unsigned long flags;
> @@ -5282,7 +5282,6 @@ static int ibmvfc_remove(struct vio_dev *vdev)
>  	spin_unlock(&ibmvfc_driver_lock);
>  	scsi_host_put(vhost->host);
>  	LEAVE;
> -	return 0;
>  }
>  
>  /**
> diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c
> index 29fcc44be2d5..77fafb1bc173 100644
> --- a/drivers/scsi/ibmvscsi/ibmvscsi.c
> +++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
> @@ -2335,7 +2335,7 @@ static int ibmvscsi_probe(struct vio_dev *vdev, const struct vio_device_id *id)
>  	return -1;
>  }
>  
> -static int ibmvscsi_remove(struct vio_dev *vdev)
> +static void ibmvscsi_remove(struct vio_dev *vdev)
>  {
>  	struct ibmvscsi_host_data *hostdata = dev_get_drvdata(&vdev->dev);
>  
> @@ -2356,8 +2356,6 @@ static int ibmvscsi_remove(struct vio_dev *vdev)
>  	spin_unlock(&ibmvscsi_driver_lock);
>  
>  	scsi_host_put(hostdata->host);
> -
> -	return 0;
>  }
>  
>  /**
> diff --git a/drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c b/drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c
> index cc3908c2d2f9..9abd9e253af6 100644
> --- a/drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c
> +++ b/drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c
> @@ -3595,7 +3595,7 @@ static int ibmvscsis_probe(struct vio_dev *vdev,
>  	return rc;
>  }
>  
> -static int ibmvscsis_remove(struct vio_dev *vdev)
> +static void ibmvscsis_remove(struct vio_dev *vdev)
>  {
>  	struct scsi_info *vscsi = dev_get_drvdata(&vdev->dev);
>  
> @@ -3622,8 +3622,6 @@ static int ibmvscsis_remove(struct vio_dev *vdev)
>  	list_del(&vscsi->list);
>  	spin_unlock_bh(&ibmvscsis_dev_lock);
>  	kfree(vscsi);
> -
> -	return 0;
>  }
>  
>  static ssize_t system_id_show(struct device *dev,
> diff --git a/drivers/tty/hvc/hvcs.c b/drivers/tty/hvc/hvcs.c
> index 3e0461285c34..80874945ded8 100644
> --- a/drivers/tty/hvc/hvcs.c
> +++ b/drivers/tty/hvc/hvcs.c
> @@ -819,7 +819,7 @@ static int hvcs_probe(
>  	return 0;
>  }
>  
> -static int hvcs_remove(struct vio_dev *dev)
> +static void hvcs_remove(struct vio_dev *dev)
>  {
>  	struct hvcs_struct *hvcsd = dev_get_drvdata(&dev->dev);
>  	unsigned long flags;
> @@ -849,7 +849,6 @@ static int hvcs_remove(struct vio_dev *dev)
>  
>  	printk(KERN_INFO "HVCS: vty-server@%X removed from the"
>  			" vio bus.\n", dev->unit_address);
> -	return 0;
>  };
>  
>  static struct vio_driver hvcs_vio_driver = {
> diff --git a/drivers/tty/vcc.c b/drivers/tty/vcc.c
> index e2d6205f83ce..5f72ebf93821 100644
> --- a/drivers/tty/vcc.c
> +++ b/drivers/tty/vcc.c
> @@ -677,7 +677,7 @@ static int vcc_probe(struct vio_dev *vdev, const struct vio_device_id *id)
>   *
>   * Return: status of removal
>   */
> -static int vcc_remove(struct vio_dev *vdev)
> +static void vcc_remove(struct vio_dev *vdev)
>  {
>  	struct vcc_port *port = dev_get_drvdata(&vdev->dev);
>  
> @@ -712,8 +712,6 @@ static int vcc_remove(struct vio_dev *vdev)
>  		kfree(port->domain);
>  		kfree(port);
>  	}
> -
> -	return 0;
>  }
>  
>  static const struct vio_device_id vcc_match[] = {
>

On Wed, Jan 27, 2021 at 6:41 PM Uwe Kleine-König <uwe@kleine-koenig.org> wrote:
>
> The driver core ignores the return value of struct bus_type::remove()
> because there is only little that can be done. To simplify the quest to
> make this function return void, let struct vio_driver::remove() return
> void, too. All users already unconditionally return 0, this commit makes
> it obvious that returning an error code is a bad idea and makes it
> obvious for future driver authors that returning an error code isn't
> intended.
>
> Note there are two nominally different implementations for a vio bus:
> one in arch/sparc/kernel/vio.c and the other in
> arch/powerpc/platforms/pseries/vio.c. I didn't care to check which
> driver is using which of these busses (or if even some of them can be
> used with both) and simply adapt all drivers and the two bus codes in
> one go.
>
> Note that for the powerpc implementation there is a semantical change:
> Before this patch for a device that was bound to a driver without a
> remove callback vio_cmo_bus_remove(viodev) wasn't called. As the device
> core still considers the device unbound after vio_bus_remove() returns
> calling this unconditionally is the consistent behaviour which is
> implemented here.
>
> Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>

Acked-by: Lijun Pan <ljp@linux.ibm.com>